Compressor blade and method of making



June 18, 1957 E. P. WARNKEN 2,796,215

COMPRESSOR BLADE AND METHOD OF MAKING Filed Aug. 19, 1952 2 Sheets-Sheet 1 INVENTOR. EL ER R M/ARNKEN BY M XML I Afifysj June 18, 1957 E. P. WARNKEN 2, 5

COMPRESSOR BLADE AND METHOD OF MAKING Filed Aug. 19, 1952 Y 2 Sheets-Sheet 2 INVENTOR.

ELMER R W4RNKEN ite COMPRESSOR BLADE AND METHOD OF MAKING Application August 19, 1952, Serial No. 305,227

2 Claims. (Cl. 230-134) This invention relates to a blade for an axial flow compressor. More particularly this invention relates to an impeller blade adapted for use in the compressor section of a jet type aircraft engine and to a machine for making such impeller blade. This application is a continuation in part of my co-pending application Serial No. 154,333, filed April 6, 1950, now matured into Patent Number 2,746,514.

Impeller blades have heretofore commonly been made of metal alloys such as alloy steels. Alloy steel blades are heavy, and, since impeller blades must travel at high speeds, only expensive and difiicultly worked alloy steels may be employed in such blades. Accordingly, an object of this invention is to provide a compressor blade formed of relatively cheap readily worked material.

When alloy steel blades fail, parts thereof may be thrown by centrifugal force at high velocity like projectiles and may seriously damage the compressor housing and surrounding apparatus. Accordingly, a further object of this invention is to provide a blade which, if it fails, will disintegrate into more or less harmless particles and therefore not destroy the compressor housing.

A furtherv object of this invention is to provide a lightweight, strong, laminated, resin-impregnated impeller blade for an axial flow air compressor.

Substantially elevated temperatures in the neighborhood of 450 F. are produced in high speed air compressors. Accordingly, a further object of this invention is to provide a laminated resinous impeller blade capable of withstanding the temperatures encountered in a high speed axial flow air compressor without failure.

A further object of this invention is to provide a laminated resin-impregnated impeller blade in which the laminations of the blade proper are substantially flat and free of sharp bends or convolutions throughout their length.

A further object of this invention is to provide an inexpensive, readily formed, laminated, resin-impregnated impeller blade having great strength and resistance to failure at high speed.

The above and other objects and features of the invention will in part be apparent and will in part be obvious from the following detailed description, and the drawings, in which:

Figure 1 is a perspective View showing a compressor blade constructed in accordance with an embodiment of this invention;

Fig. 2 is a perspective view showing the compressor blade illustrated in Fig. 1 prior to trimming to finished shape;

Fig. 3 is a sectional View taken along a line IIIIII in Fig. 1;

Fig. 4 is a diagrammatic view in side elevation show- I Patented June 18, 1957 Fig. 6 is a view similar to Fig. 5 but showing a different arrangement of laminations;

Fig. 7 is a view partly in side elevation and partly in vertical section of a machine for forming the compressor blade illustrated in Fig. 1.

Fig. 8 is a perspective view of a member for forming the root section of a blade constructed in accordance with another embodiment of this invention.

Fig. 9 is a diagrammatic view of an assembly for forming a blade including the member shown in Fig. 3; and

Fig. 10 is a diagrammatic view in section taken along a line XX in Fig. 9.

In the following detailed description, and the dra ings, like reference characters indicate like parts.

In Fig. 1, a compressor blade is shown which is con structed in accordance with this invention. The compressor blade includes a main or airfoil portion 10 and a root 12. Both main portion 10 and root 12 are formed from resin-impregnated laminations of glass fibre cloth molded to the shape shown. When the blade is first removed from the mold, the blade has the appearance shown in Fig. 2, having irregular edges or fiash 13 which may be trimmed away to form the completed blade shown in Fig. 1. The resin preferably is a phenol-formaldehyde resin.

The blade is molded from a plurality of resin-impregnated laminations having resin carried to a B-stage or semi-cured state. The laminations are arranged in the manner illustrated in Figs. 4 and 5. As shown in Figs. 4 and 5, the main portion of the blade is formed from a plurality of substantially fiat laminations 14 which are mounted one on top of the other in a stack or pack. At .the root end of the pack of fiat laminations, a pair of convolutely wound laminations 16 are disposed on opposite sides thereof. As shown in Fig. 4, the convolutely wound laminations extend transversely of the flat laminations. When the blade is molded, the convolutely wound laminations 16 form root 12 of the blade, and the flat laminations form main portion 19 of the blade.

As shown in Fig. 5, the flat laminations vary in width, the inner laminations being somewhat narrower than the outer laminations so that there is a greater thickness of laminations near and slightly spaced from the center line of the blade than at the edges. The fiat laminations may be held together by a staple 17 during molding. When the laminations are molded, the main portion is formed into an airfoil as shown in Fig. 3.

It is not necessary that the flat laminations be arranged precisely as shown in Fig. 5. An alternate arrangement of the fiat laminations is shown in Fig. 6. In the arrange ment shown in Fig. 6, central laminations 18 are somewhat wider than the outer laminations 19. However, the same effect is obtained as with the arrangement shown in Fig. 5 when the blade is molded, and the number of laminations adjacent the center line of the blade is greater than at the edges in both arrangements. The arrangement shown in Fig. 5 is the preferred arrangement in that a pair of wide laminations 21 cover all inner laminations, and the wide outer laminations cover the side edges of the inner laminations.

Preferably, the outer laminations are formed from glass fibre cloth having a somewhat closer weave than the inner laminations. In a preferred form of this invention, the inner laminations may be cloth woven from glass fibres having 40 x 39 threads to the inch while outer or covering laminations 21 may have approximately 58 x 57 threads to the inch. In the preferred form, the cloth of the convolutely wound laminations 16 may have approximately 48 x 38 threads to the inch. In the drawings, for ease of illustration, only a few flat laminations are shown. However, it is to be understood that the number of flat laminations may be increased or decreased as required to form a blade of desired thickness. For example, a blade inch thick may contain about 11 layers or laminations.

I11 Figs. 9 and 10 are shown a pack of laminations 22 and a root-forming member 23 which may also be used in forming a blade of the type shown in Figs. 1 and 3. The pack of laminations 22 may be similar in form to the packs of laminations shown in Figs. and 6. Rootforming member 23 takes the place of the convolutely wound laminations. The root-forming member, as shown in Fig. 8, is formed of a pack containing a plurality of flat laminations stacked one on the other. An opening 24 is cut through the root-forming member 23 to receive the pack of laminations 22, as shown in Figs. 9 and 10.

The assemblies of laminations illustrated in Figs. 4-10 inclusive may be molded in a machine of the type illustrated in Fig. 7 to form the intermediate blade construction illustrated in Fig. 2. In the following, the formation of a blade from the assembly shown in Figs. 4 and 5 will be described in detail. However, it is to be understood that a blade can be formed from each of the other assemblies in a similar manner.

The machine illustrated in Fig. 7 includes a base 26 upon which a die support frame 27 is carried. Frame 27 supports a stationary press plate 27, on which is mounted a stationary die 28 having an upwardly facing die face 29. In addition, the plate 27' supports two pillars 31 at opposite ends of stationary die 23 which form guides for a floating platen 32. The platen 32 carries a movable die 33 which is vertically reciprocable with platen 32 toward and away from die face 29. Movable die 33 has a lower die face 34 opposite die face 29, and die faces 29 and 34 are adapted to engage flat laminations 14 to form the flat laminations into the main or airfoil portion of the blade. The dies 28 and 33 are cut away at one end, as indicated at as and 37, respectively, to provide a slot into which the portion of the pack of laminations 14 which carries staple 17 may extend so that the ends of the laminations 14 to the right of die faces 29 and 34, as shown in Fig. 7, are exposed during the molding.

At the left hand end of die face 23 of stationary die 28, a vertical slot 38 is provided through which a lower, movable, root-forming die 39 is reciprocable. Opposite slot 38 main movable die 33 is cut away to form a slot 41 through which an upper movable, root-forming die 42 is vertically reciprocable. The root-forming dies 39 and 42 have co-operating die faces which form the convolutely wound laminations into the root portion of the blade. The root forming dies are equipped with stop shoulders 40 which can engage co-operating stop shoulders 40 on the main dies for limiting the advance of the root-forming dies. The stops are arranged to prevent the root-forrning dies from extending past the main die faces so that the root-forming dies do not engage the flat laminations.

Stationary die 28 includes a gripping shoe 43 to the left of solt 38 (Fig. 7). Shoe 43 is disposed opposite a corresponding shoe 44 on main movable die 33. The shoes 43 and 44 grip and hold the left hand end of the pack of laminations 14 as die faces 29 and 34 mold the airfoil portion of the blade so that, when the root-forming dies are advanced together upon the convolutely wound laminations 16, the flat laminations 14 are held flat and are not caused to fold or buckle as the root portion of the blade is formed.

The machine illustrated in Fig. 7 is provided with hydraulically powered cylinders for operating the movable dies. An hydraulic cylinder 46 mounted on frame 27 has its piston rod 47 connected to platen 32. The platen is moved downwardly when fluid under pressure is delivered into the upper end of the cylinder from a supply line 48. The platen 32 is raised when pressure is apto the lower end of the cylinder by supply pipe 56. When platen 32 is moved downwardly it is forced against stationary die 28 to apply pressure to the flat laminations and thereby mold and form them into the main or airfoil portion of the blade. As dies 28 and 33 mold the main or airfoil portion of the blade, shoes 43 and 44 squeeze and hold the left hand end of the pack of laminations so that the pile of flat laminations is held at both ends. While so held the root end of the pack lies between the root-forming dies. The root-forming dies are actuated by power cylinders 51 and 52. When the main movable die has been brought into engagement with the flat laminations, fluid under pressure is delivered into the lower and upper ends respectively of cylinders 51 and 52 through feed lines 53 and 54 whereby the piston rods thereof force the root-forming dies into engagement with the convolutely wound laminations and form the root portion of the blade.

As shown in Fig. 7, cylinder 51 is attached to the stationary framework of the machine, while cylinder 54 is attached to and rides up and down with floating platen 32. The cylinders 51 and 52 are provided with pressure lines 57 and 58, respectively, whereby fluid under pressure delivered to the cylinders causes return of the movable dies to the retracted positions shown in Fig. 7.

The operation of the machine in molding the laminations into a compressor blade will be clear from the foregoing detailed description and the drawings. The laminations are preferably assembled in the manner shown in Figs. 4 and 7. The convolutely wound laminations are preferably disposed as shown in Fig. 7 with the free lengthwise edges of the convolutely wound laminations abutting the outer laminations of the pack of flat laminations so that the free edges of the convolutely wound laminations are covered when the blade is molded. The flat laminations are gripped and formed by the main dies prior to molding of the root portion of the blade. Thereafter, the root-forming dies are advanced toward each other to grip and mold the convolutely wound laminations 16 into the root of the blade. The dies may be heated to an appropriate temperature at which the resin impregnant can flow so that a firm and lasting bond is provided at the root of the blade between the convolutely wound laminations and the fiat laminations. When the blade has been molded, the dies are retracted, and the blade has the appearance shown in Fig. 2. The blade then can readily be finished by trimming and removing the flash 13 to form a finished blade as shown in Fig. 1.

The blades of the invention are substantially stronger per unit weight than a conventional steel alloy blade. Moreover, the blade does not fail by breaking or shearing off into large pieces. Test results have indicated that the blades of the present invention are superior in fatigue properties to a conventional alloy steel blade. Thus, it requires more protracted misuse of the present blade to cause its failure than is required to cause failure of a steel blade.

For high velocity axial flow air compressors such as are used in the compressor sections of jet-type aircraft engines, the blades of this invention are preferably forrncd of glass fibre cloth laminations impregnated with a phenol-formaldehyde type resin. In other types of air compressors, blades of the same form may be constructed using other laminating fabrics and resins where the tem peratures encountered are less extreme.

One form of compressor blade has been illustrated, but it is to be understood that compressor blades of other forms may be prepared in accordance with this invention and that the construction of the dies of the machine for forming the blades may be varied to form. other shapes of blades Without departing from the spirit and scope of the appended claims.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A method of molding an impeller blade having an elongated airfoil portion and an enlarged root at one end of the airfoil portion which comprises forming a stack of substantially parallel resin-impregnated vaneforrning laminations and a stack of root-forming laminations having an opening therethrough of suflicient size to receive one end portion of the stack of elongated laminations, mounting the stack of root-forming laminations on said end portion of the stack of elongated laminations, applying melding pressure to the elongated laminations to form the airfoil portion of the blade into a solid elongated airfoil Without substantially twisting the elongated laminations, and applying separate molding pressure to the root-forming laminations to form the enlarged root. 2. A molded impeller blade which comprises a plurality of substantially parallel elongated blade forming laminations disposed in a stack one on the other and a stack of annular root-forming laminations having an opening therethrough, one end of the stack of blade forming laminations projecting into the opening of the stack of root-f0rming laminations, the laminations being impregnated with a resin, the elongated laminations being molded to a solid airfoil configuration, the elongated laminations being substantially flat and untwisted, the root-forming laminations being molded to a root projecting outwardly of the airfoil at one end thereof.

References Cited in the file of this patent UNITED STATES PATENTS Leblanc Aug. 13, Kempton Aug. 30, King Feb. 7, Kemp Oct. 2, Gudge Aug. 30, Mansur Apr. 5, Heath Sept. 6, Kotzin Apr. 14, Lougheed Dec. 12, Di Cesare Sept. 8, Pitcairn Mar. 11, Bitterli et a1. Dec. 9, Overholt May 19, Morrison Jan. 24,

FOREIGN PATENTS Great Britain Apr. 7, France Apr. 29, 

1. A METHOD OF MOLDING AN IMPELLER BLADE HAVING AN ELONGATED AIRFOIL PORTION AND AN ENLARGE ROOT AT ONE END OF THE AIRFOIL PORTION WHICH COMPRISES FORMING A STACK OF SUBSTANTIALLY PARALLEL RESIN-IMPREGNATED VANEFORMING LAMINATIONS AND A STACK OF ROOT-FORMING LAMINATIONS HAVING AN OPENING THERETHROUGH OF SUFFICIENT SIZE TO RECEIVE ONE END PORTION OF THE STACK OF ELONTATED LAMINATIONS, MOUNTING THE STACK OF ROOT-FORMLNG LAMINATIONS 